To assess initiatives to manage the cost and outcomes of specialty care in organizations that participate in Medicare accountable care organizations (ACOs). Cross-sectional analysis of 2023 ACO survey data. Analysis of responses to a 12-question web-based survey from 101 respondents representing 174ACOs participating in the Medicare Shared Savings Program or the Realizing Equity, Access, and Community Health ACO model in 2023. Improving specialist alignment was a high priority for 62% of the 101 respondents and a medium priority for 34%. Only 11% reported that employed specialists were highly aligned and 7% reported that contracted specialists were highly aligned. A subset of ACOs reported major efforts to engage specialists in quality improvement projects (38%) and to convene specialists to develop evidence-based care pathways (30%). They also reported supporting primary care physicians through providing specialist directories (44%), specialist e-consults (23%), and sharing specialist cost data (20%). The most common challenges reported were the influence of fee-for-service payment on specialist behavior (58%), lack of data to evaluate specialist performance (53%), and insufficient bandwidth or ACO resources to address specialist alignment(49%). Engaging specialists in accountable care is an emerging area for ACOs but one with numerous challenges. Making better data on specialist costs and outcomes available to Medicare ACOs is essential for accelerating progress.